perl生成匹配正则表达式的字符串 [英] perl to generate string to match regex

问题描述

我试图找到一种方法来生成与正则表达式匹配的字符串，例如以下正则表达式:

I try to find a way to generate string that matches regex, for example, the following regex:

[A-Z]{6,6}[A-Z2-9][A-NP-Z0-9]([A-Z0-9]{3,3}){0,1}

我试过了Cpan上的一些perl模块，这些模块不起作用: ->字符串::随机 -> Regexp :: Genex

There are some perl modules on Cpan which I tried that doesn't work: -> String::Random -> Regexp::Genex

不支持String :: Random显示(). Regex :: Genex对此字符串报告错误($ regex).

The String::Random shows () is not supported. Regex::Genex reports error on strings($regex) with this one.

感谢您的帮助！

推荐答案

如果您想要一个通用的解决方案，并且不愿意尝试修复String :: Random，则可以使用

If you want a general solution and you aren't will to work towards fixing String::Random, you could use a large number of monkeys.

use strict;
use warnings qw( all );
use feature qw( say );

my $pattern = qr/^[A-Z]{6}[A-Z2-9][A-NP-Z0-9](?:[A-Z0-9]{3})?\z/;

my $min_len =  0;
my $max_len = 15;
my @syms = map chr, 0x20..0x7E;

my $s;
while (1) {
   $s = join '', map { $syms[rand(@syms)] } 1..$min_len+rand($max_len-$min_len+1);
   last if $s =~ $pattern;
}

say $s;

此解决方案按字面意义生成完全"随机字符串，直到找到匹配的字符串为止. 这是一种糟糕的方法，而且速度可能很慢.

This solution literally generates "completely" random strings until it find one that matches. It's an awful approach, and it can be quite slow.

您可以通过限制随机字符串生成器(通过$min_len，$max_len和@syms)来加快解决方案的速度.也就是说，您对这些限制越多，此解决方案将支持的模式越少.例如，对于示例模式，使用$min_len = 8; $max_len = 11; @syms = ( 'A'..'Z', '0'..'9' );会更快，但是使用这些参数可能会阻止它对其他模式起作用.

You can speed it up the solution by restricting the random string generator (via $min_len, $max_len and @syms). That said, the more you restrict these, the fewer patterns this solution will support. For example, using $min_len = 8; $max_len = 11; @syms = ( 'A'..'Z', '0'..'9' ); will be insanely faster for the example pattern, but using those parameters might prevent it from working for other patterns.

还请注意，这种方法会使可能性降低.某些匹配的字符串比其他字符串更可能生成.例如，给定^[A-Z]{1,3}\z的猴子比AAA产生A的可能性高得多.

Also note that this approach skews the odds. Some matching strings are more likely to be generated than others. For example, the monkeys are incredibly more likely to produce A than AAA given ^[A-Z]{1,3}\z.

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